BURN WOUND INFECTIONS - CURRENT STATUS

The burn wound represents a susceptible site for opportunistic coloniz ation by organisms of endogenous arid exogenous origin. Patient factor s such as age, extent of injury, and depth of burn in combination with microbial factors such as type and number of organisms, enzyme and to xin production, and motility determine the likelihood of invasive burn wound infection. Burn wound infections can be classified on the basis of the causative organism, the depth of invasion, and the tissue resp onse. Diagnostic procedures and therapy must be based on an understand ing of the pathophysiology of the burn wound and the pathogenesis of t he various forms of burn wound infection. The time-related changes in the predominant flora of the burn wound from gram-positive to gramnega tive recapitulate the history of burn wound infection. Proper clinical and culture surveillance of the burn wound permits early diagnosis of gram-positive cellulitis, and the stable susceptibility of P-hemolyti c streptococci to penicillin has eliminated the threat of this once Co mmon burn wound pathogen. Selection and dissemination of intrinsic and acquired resistance mechanisms increase the probability of burn wound colonization by resistant species such as Pseudomonas aeruginosa. Eve n so, effective topical antimicrobial chemotherapy and early burn woun d excision have significantly reduced the overall occurrence of invasi ve burn wound infections. Individual patients; usually those with exte nsive burns in whom wound closure is difficult to achieve, may still d evelop a variety of bacterial and nonbacterial burn wound infections. Consequently, the entirety of the burn wound must be examined on a dai ly basis by the attending surgeon. Any change in wound appearance, wit h or without associated clinical changes, should be evaluated by biops y. Quantitative cultures of the biopsy sample may identify predominant organisms but are not useful for making the diagnosis of invasive bur n wound infection. Histologic examination of the biopsy specimen, whic h permits staging the invasive process, is the only reliable means of differentiating wound colonization from invasive infection. Identifica tion of the histologic changes characteristic of bacterial, fungal, an d viral infections facilitates the selection of appropriate therapy. A diagnosis of invasive burn wound infection necessitates change of bot h local and systemic therapy and, in the case of bacterial and fungal infections, prompt surgical removal of the infected tissue. Even after the wounds of extensively Burned patients have healed or been grafted , burn wound impetigo, commonly caused by Staphylococcus aureus, may o ccur in the form of multifocal, small superficial abscesses that requi re surgical debridement. Current techniques of burn wound care have si gnificantly reduced the incidence of invasive burn wound infection, al tered the organisms causing the infections that do occur; increased th e interval between injury and the onset of infection, reduced the mort ality associated,vith infection, decreased the overall incidence of in fection in burn patients, and increased burn patient survival.